Making lamp stems



MayV 11, 1943. 'cl WIENER MAKING LAMP STEMS Filed Dec. so, 195s A! 9.1km

'ATTORNEY INVENTOR c'. WEA/Efe. BYL

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' connecting stemof the tube.

that of fluorescent tubes flanking the lateral Patented May 11,1943

' zjaiass y MAKING LAMPy sTEMs" Charles Wiener, Newark, N. J-.',assgnorto Westinghouse Electric. '& Manufacturing Company,: East.Pittsburgh, Pa., a .corporation of Pennsyl--.v

Vania Appn'eatimpeeemte so, 193s, senat No. 24am The invention relatesto making lamp stems and especially to the making of vitreous@ or glassstems for tubes of the fluorescent type.

An object of the invention is to make lamp stems that are uniformly thinand which will not crack when heat is.v applied for sealing@ f Anotherobject is to adapt stein makt paratus for the production ofV uniformyglass stems.

Other objects and advantages of the invention will be apparent fromthefollowing description anddrawing, in which:

Fig. 1 is a. view in cross-section through lone end of a fluorescentlamp'illustrating fthe'. type of seal and stem accomplished by myinvention..

Fig. 2 is a view on lines II--H of Fig, 1'.

Fig. 3 is a cross-section through a spindle and associated apparatuswith elements -of the stem in place.

Fig. 4 is a view on lines IV-IV of- Flg. 3. Figs. 5, 6, and 7 are viewssimilar to that oi Fig. 3 -illustrating various stages in forming thestem accordingto my invention.

Certain types of tubes require a thin andv deli-` cate stem. Such a typeof tube `is that of a fluorescent lamp where the requirements of beau-Ity will not permit the usual thick' glass press en'- closed by thecumbersome screw-threaded base. The stems on these fluorescent ,tubesmust be of a delicate formation especilally rwhere it is necessary thatthe tube'itself present no outline of structure displeasing to the'eyeby an awkward Such use, being edges of the mirror of a Vanity-wherecumberpleasing effect presented by the rest of the-object. f

It is also important that where uniformly 'thin stems are utilized thatthese, stems have a shape that will be strong and also that the! methodof assembling thesestems be suitable for massv production. My inventionaccomplishes all of these objects in providing, by method suitable formass production, a glassstern for fluorescent lamps especially thosethat are both Auniformly thin and yet strong enough for the purpose forwhich they are made.

In Fig. 1, I have illustratedl one end of a fluorescent tube having atubular casing IIJ- with an interior fluorescent coating II thereon.This t'ubular member is sealed to a stem designated in general by I2 andcomposed of a filament I3 having two leads I4 and I' sealed through anannular reentrant portion I6 about the tubulation I'I.

mrtg; 3, I heveiuustreted me modification' of stem making apparatusto-accomplish the.forf l Y mation of the stemaccordingto' my preferredmethod and also the elementsof'. the stemawaita 5ing,'assembly'.thereon.V The spindle'. 20.. of vthe stem`v makingdevicefhas two `holes y 2I and;22= drilled on opposite'lsidesV of. a`central :largenhole or pocket 23. ri These two holes 2 I and 22 are cfadiameter to `act as pockets to containthe conductors I4 and I5 thereinandthe central pocket 23 contains the ftubulation II which preferablyhas aj preformed con'ical'flare I Bfat the upper' por TheV depthsof "thebottoinclosed l holes or'pockets 2|, 22, and 23 .are'suchthatthe f l rimof the flare vrI8- of the- .tubulation:.almost touchesrth'e portion 24ofthe'conductors Iland I5 and thisl portion is preferably of .thefamiliar-` copper clad nickel-iron'alloy 4commonly referred- 5 tionthereof.

to as Dumet The upper portion ofthe con- 2'0 ductors may be of nickel asmay alsobe the portion below the Dumet portion. 24. This Vlower portioncan also be of any other suitable lconf ducting materialsuch as copper..'I he spindle 2l has a conical upper surface v 25 adapted'tp receive 25the frustofconical portionof a aretube 26 ha.v'

ing a tubular or generally cylindr cal ycollar 2'Iv which is of such adiameter that it closely surrounds the wires I4 and vI5 held in theirpockets 2I and 22. AThe' tubular collar 21 terminates at its rim 28 ashort distance above or beyond the flange. I8 of the-.tubulation tubeII. When the flare tube -26 hasbeen put in place and a. perforatedthimble 30 `fits over vthe top surface, then y this thimble centers`said tube by closely ffittinggf l bothit andthe spindle.2ll or a sleeve3I secured some ends on the fluorescent tube would spoil'the i e`openings 32 and .33 as disclosed in Figs. 44' and 5,

which are not pockets but extend from the upper 40 conical surface of.the spindle between the tu'- I bulation II and the contact of the aretube26` therewith to a conduit 34 having a gaseous Imedium such as airunder regulated pressure. These y y two openings 32 and 33 may belocated symmetrica] with the pockets or bottom closed holes 2I and 22forthe conductors I4 and' I5 as illus-Y trated in Fig. 4.

Vfris disclosed in Fig. 5, the spind1e zo 1ere- ,volved and heat such asfor.example,-a gas flame /35, directed against me .upper edge 2s ef thetubular collar portion'ZI.

`The heat', from the llame 35 melts down the upper edge portion 28 ofthe glass, against the Dumetf portion 24 `of the conductors. I4' and I5and also against the adjacent edge of the 6. The application of thehea-t, accordingly, forms a seal between the tubulation I'l and the naretube 26. Normally this seal would be in the form of a sharp, inverted Vwith thick sides. Such a'V-shaped seal would be very weak and apt tocrack easily in thecrotch of the V. Furthermore the annealingfof theglass forming the Y seal would'be very slowbec'ause of the thickness lof the melted glass and strains might exist in the seal as a result.

The application of air or of other gases such as the inert gas nitrogenunder pressure, through the openings 32 and 33 will round out theannular portion I6 while still soft. asdisclosed in Fig. 7, into agentle arched or toroidalcurve that avoids strains present in the seal.Fury nare I8 of thetubulation l1 as disclosed in Fig. above the upperilaredend portion of saidex-f haust tube, disposing lead-in conductormeans between said collar and flared portions, applying heat adjacentthe upper edge of said collar portion sufficient only to draw said upperedge portion inwardly and unite it by fusion with said open flared endportion of said exhaust tube,` to form a seal, and rounding and thinningthe Afused vitreous seal betweenA said portions by applying iluidpressure between said exhaust tube and collar, whereby the junction.therebetween thinned to approximately the normal thickness thermocrethis gaseous pressure accomplishes the Y result of providing a uniformlythin wall in the annular'portion where the conductors are sealedtherein. Due to the thickness Vof the wall, the

glass will have a rapid rate of annealing and thisV rapid 'rate oiannealing willv remove the possibility offstrains remaining in theglass. i A

It is apparentthat modiications may be made in. the vspecific form andarrangement of the various elements and the method of their as- Semblky.s i

l. The -method oi' making a stem for a lamp comprisingy disposing avitreous flare tube having s. frusto-conical portion anda generallycylindrical collar portion around a vertically dis- Y posed vitreousexhaust tube having its upper end portion open and ilared, with thefrusto-conical portion oi .the flare tube encircling an intermediateportion of. said exhaust tube and the generally cylindrical collar'portion extending ofthe parts.

'2. The method of making a stem for a. lamp comprising heating. andexpanding the upper end .portion of .a vitreous exhaust tube to form anoutwardly flared open end portion, disposing a vitreous flare tubehaving a. frusto-conical portionand a generally cylindrical collarportion aroundA said exhaust tube when vertically disposed with thefrusto-conical portion of the flare tube encircling an intermediateportion of said exhaust .tube and the generally cylindrical collarportion extending above the upper portion oi said'exhaust tube,disposing lead-in conductor means betweensad collarpand ilared portions,

applying heat adjacent v'the upperedge of said collar portion'suillcient only to drawsaid upper edge portionV inwardly and unite it byfusion with saidvopen flared end portion ofy said vexhaust tube, to forma seal, and rounding and thinning the -fused vitreous .sealy betweensaid portions by applying fluid pressure between said exhaust tube andcollar, whereby the junction A i therebetween isv .thinned toapproximately the normal thickness of the parts.

CHARLES WIENER.

